1. Field of the Invention
The present invention relates to the compounds generating strong acids (described hereafter as “acid generators”), decomposed by heat and the composition of thin films containing the same. Particularly, the present invention relates to the composition which maintains the thin film notwithstanding the severe condition because of the cross linking reaction carried out by the generated acid.
2. Description of the Related Arts
In recent years, great interests are shown on the thin film as the industrial sectors develop rapidly. The thin film technology is used in the processes of ultra fine semiconductors as well as in the household electronic products and furniture. For example, an organic thin film composition is used in the manufacturing process of semiconductor to shield the reflection of light from the bottom layer and to increase the adhesive strength to the substrate. In case it is not shielded, deformation in the ultra fine pattern occurs. When the substrate coated by thin film is exposed to the ArF eximer laser, the light of 193 nm wave length is reflected by the substrate, making the patterns change. The thin film technology is utilized also in the manufacturing process of LCD, to protect the top part of the color filter and the thin film is used as a means to protect the surface of the household electronic products and the furniture.
The technology of making thin films is categorized into two methods according to the catalyst employed. One method is the technology using radical initiator. The frequently used resin in this case is acrylate derivatives. The functional group participating in the reaction is the unreacted acrylate. The other method is the technology using cation catalyst in making the thin films. The resin generally used in the process is the acrylates derivatives containing epoxy group. The epoxy group easily goes into cross linking reaction by strong acids.
The technology using radical initiator to make the thin films has to be blocked from oxygen in the air, making the process problematic, while the technology of using cation catalyst has the advantage of not needing the oxygen blockade.
The cation catalysts are grouped into the compounds according to their characteristics whether generation of acid is by light or by heat. The compounds generating acid by light include iodonium salts, sulfonium salts, phosphonium salts, diazonium slats, pyridinium salts and amides. The compound generating acid by heat includes sec-alkyl-p-toluenesulfonate.
The acid generators by heat or light has to possess both appropriate stability and the property of decomposing by heat according to the uses. When the acid generator decomposes easily by heat or during storage period, it loses the product value, while it also loses the product value when it is too stable to heat because it lacks in reactivity.